Good points, Goeroge.
I wouldn;t worry too much about the polls yet. UK Polling Report, which is a seething mass of psephological anoraks, dissects the latest YouGov poll and concludes:
So while the BNP support is up, it is nothing significant. 2-3% has been pretty much the norm for their support over the last couple of months, and the most recent YouGov/Telegraph poll at the end of September also had them at 3%...

...Anyway, the poll will really be looked at for evidence of how the BNP's Question Time appearance has gone down, rather than the main parties. As well as voting intention, YouGov asked whether people had positive or negative opinions of the smaller parties – questions that it last asked in June straight after the European elections. Back then 11% of people had a positive impression of the BNP and 72% a negative impression, today's figures are 9% positive and 71% negative, so no sign of any improvement in people's opinion of the BNP either. Despite all the hoohah and protests, despite the millions of people who watched Question Time, it doesn't seem to have made any significant difference to how the public view them, or how likely they are to support them (or at least, not yet).